javascript

Chapter 2: JavaScript in HTML
For information on more ways to achieve functionality similar to that of the defer attribute, see
Chapter 12 .
Changes in XHTML
Extensible HyperText Markup Language, or XHTML, is a reformulation of HTML as an application
of XML. The rules for writing code in XHTML are stricter than those for HTML, which affects the
< script/ > element when using embedded JavaScript code. Although valid in HTML, the following
code block is invalid in XHTML:
< script type=”text/javascript” >
function compare(a, b) {
if (a < b) {
alert(“A is less than B”);
} else if (a > b) {
alert(“A is greater than B”);
} else {
alert(“A is equal to B”);
}
}
< /script >
In HTML, the < script > element has special rules governing how its contents should be parsed; in
XHTML, these special rules don ’ t apply. This means that the less - than symbol ( < ) in the statement a < b
is interpreted as the beginning of a tag, which causes a syntax error because a less - than symbol must not
be followed by a space.
There are two options for fixing the XHTML syntax error. The first is to replace all occurrences of the
less - than symbol ( < ) with its HTML entity ( & lt; ). The resulting code looks like this:
< script type=”text/javascript” >
function compare(a, b) {
if (a &lt; b) {
alert(“A is less than B”);
} else if (a > b) {
alert(}A is greater than B”);
} else {
alert(“A is equal to B”);
}
}
< /script >
This code will now run in an XHTML page; however, the code is slightly less readable. Fortunately, there
is another approach.
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